Board for manufacturing a BGA and method of manufacturing semiconductor device using thereof

ABSTRACT

A device containing a flat member is provided, having a pattern for a bonding pad, a wiring, and an electrode, by half-etching through the flat member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a board for manufacturing a BGA (BallGrid Array) and a method for manufacturing a semiconductor device usingthereof.

2. Description of the Related Art

An IC package for a portable equipment or a small, hi-density mountingequipment has advanced in recent years. Details of these advances aredescribed in CSP technology, and mounting material and device supportingthe technology—special issue of DENSHI ZAIRYO (p.22, Set. 1998).

FIGS. 15A and 15B show a BGA using a flexible sheet 50 as an inter-poserboard. FIG. 15A is a plan view, and FIG. 15B is a section view cut atA—A line.

On the flexible sheet 50, a copper foil pattern 51 is bonded by anadhesive. An IC chip 52 is fixed on the flexible sheet 50 and a bondingpad 53 is formed around the IC chip 52 with the copper foil. Asolder-ball connecting pad 55 is formed through a wiring 54, which isintegrated with the bonding pad 53. A solder-ball is then formed on theconnecting pad 55.

In FIG. 15A, the flexible sheet 50 is indicated peripherally in solidline, and the IC chip 52 is indicated by a rectangle in solid line. Atinside the bonding pads 53 formed around the IC chip 52, the solder-ballconnecting pads 55 are arranged in matrix-shape.

At a rear side of the solder-ball connecting pads 55, an opening portion57 is formed by processing the flexible sheet 50, and the solder-ball 56is formed through the opening portion 57.

The flexible sheet 50 is used as a ceramic board and printed board, anda member is processed thinly among these boards. However a flexiblesheet is expensive compared to a ceramic board and printed board.Moreover, using these boards would increase the cost of a BGAsubstantially including the cost to machine the opening portion 57.

Thin and lightweight types are desired for a semiconductor device usedin a portable equipment and also for a BGA. However, generally theprocess of forming a Cu foil pattern, of mounting the IC chip 52, and ofbonding wire 58 would require the use of a flexible sheet 50 as asupporting board. Therefore, the flexible sheet 50 would have to be usedin view of the manufacturing processes.

Moreover, the Cu foil pattern tends to deform or peel off because the Cufoil pattern is bonded with adhesive on the flexible sheet 50. As thenumbers of pads of the IC chip 52 increases year and year, making finerCu foil patterns is needed with the BGA. Consequently, bonding area ofthe wiring 54 and bonding pad 53 are decreased, thereby becoming moresusceptible to deformities or peeling of the Cu foil pattern.

Furthermore, manufacturing a BGA requires much time because asemiconductor manufacturer would have to inform a flexible sheet vendoron the designated pattern data, the flexible sheet manufacturer wouldthen have to manufacture the flexible sheet, and the semiconductormanufacturer would then purchase the completed flexible sheet.Accordingly, manufacturing a semiconductor device as a product wouldrequire a considerable amount of time. The semiconductor manufacturercannot deliver the BGA to a user in short time.

Also, heat from the IC chip 52 is insufficiently radiated because theflexible sheet 50 is interposed between the Cu foil pattern 51 and theIC chip 52.

SUMMARY OF THE INVENTION

An embodiment of the present invention is a board for manufacturing aBGA, having a first face including a flat face and a second face formedopposite to the first face, which has a flat face. On the second face, afirst conductive film has substantially the same pattern as a bondingpad provided at a periphery of a semiconductor element mounting area,and a wiring extends to the semiconductor element mounting area in onebody with the bonding pad. An electrode is also formed in one body withthe wiring.

Another embodiment of the invention is a flat member having a first faceincluding a flat face and a second face formed opposite to the firstface, which has a flat face. On the second face, a photo resist havingsubstantially the same pattern as a bonding pad is formed at a peripheryof the semiconductor element mounting area. A wiring extends to thesemiconductor element mounting area in one body with the bonding pad. Anelectrode is formed in one body with the wiring. In another embodiment,at an area corresponding to the bonding pad, a conductive film isformed. The photo resist is provided to cover the film.

By half-etching through the conductive film or the photo resist formedon the flat board, a conductive pattern is formed, supported by the flatmember. Therefore, a semiconductor manufacturer with etching facilitiescan manufacture a semiconductor device consistently from a flat member.

Because a flat member is used as a supporting board in fixing asemiconductor element, an electric connection is formed using a bondingwire, and a sealing is provided by using insulating resin, and aconventional flexible sheet as a supporting board is not need. Althoughthe bonding pad is thin and exists in island-shape, and the wiring isarranged in a rather precarious state because of its length andthinness, deformation such as bending or peeling is avoided because theyare made in one body with the flat member.

Because of half-etching, the pattern of the flat member is not removedat its face, and the interval between the conductive patterns can bemade narrow so that a finer pattern can be formed. Further, separatingthe pad and the wiring is possible by polishing or etching the back ofthe flat member after entirely fixing the flat member with an insulatingresin. The pattern is arranged in a designated position without a gapand deformation even with long wirings.

In the case of half-etching the photo resist as a mask, a wire bondingis provided by forming a conductive film at the bonding pad.

In another embodiment, a pattern can be as substantially the same as aguide pin or a guide hole where the guide pin is inserted at side partsof the flat member facing each other so that a die mounting area of theflat member is carried out in high accuracy at molding.

In another embodiment, the flat member includes a conductive foil andthe conductive film includes material different from the conductivefoil.

By forming the conductive film, the side face of the projection is bentand further eaves are formed at the conductive film. Therefore, abonding pad and a wiring being conductive pattern are buried ininsulating resin with an anchoring effect.

Another embodiment of the invention is a flat member having a first faceincluding a flat face and a second face having a projection formed indesired heights and being formed opposite to the first face. A bondingpad is provided at a periphery of a semiconductor element mounting area.A wiring extends to the semiconductor element mounting area in one bodywith the bonding pad. An electrode is provided in one body with thewiring.

A conductive film can be formed at a surface of said projection or atleast at an area corresponding to the bonding pad.

The flat member includes a conductive foil, and the conductive filmincludes material different from the conductive foil.

Manufacturing a flat member provided with projections, a mountingsemiconductor, an electric connection to a pad, and sealing the abovemembers are all possible within the facilities of a semiconductormanufacturer. Therefore, a flat member can be provided by a materialmanufacturer and the semiconductor manufacturer can manufacture asemiconductor device of a BGA type.

Further, the flat member may be transferred easily without shifting andcan bond well to other elements.

Because a flat member is used as a supporting board in fixing asemiconductor element, an electric connection can be formed by using abonding wire, and a sealing can be formed by using insulating resin.Thus, a conventional flexible sheet can be obviated. Although thebonding pad exists in island-shape and is arranged in a precariousstate, deformation such as bending or peeling is avoided because theflat member is made in one body. Although bending or peeling may occurwhen there are long extended wirings, this problem is avoided when thebonding pad is provided in one body with the flat member.

The interval between the pads or the conductive patterns is made narrowso that a thin pattern can be formed. Further, separating the pad, diepad, and the wiring is possible by polishing or etching the back of theflat member after fixing the member with insulating resin. The patternis arranged in a designated position without a gap.

A projection of a pattern can be as substantially the same as a guidepin or guide hole where the guide pin is inserted.

The designated pattern includes a projection in matrix shape so thatmass production is possible.

The flat member includes Cu, AL, Fe—Ni alloy, a layered product ofCu—AL, or a layered product of Al—Cu—Al.

A side face of the projection has an anchoring structure.

The conductive film can provide eaves at an upper face of theprojection.

The conductive film made of at least one of Ni, Au, Ag, and Pd, has ananchoring effect. Also, wire bonding and die bonding are possible.

Another embodiment of the invention is a flat member having an entireflat back face corresponding to a resin sealing area and a front facehaving a projection at an area surrounded by an upper die and acontacting area. The projection has a bonding pad provided at aperiphery of a semiconductor element mounting area, a wiring extendingto the semiconductor element mounting area in one body with the bondingpad, and an electrode provided in one body with the wiring. At least thearea surrounded by a contacting area with the upper die provides asealing space with the surface and the upper die.

Another embodiment of the invention is a flat member having an entireflat back face corresponding to a resin sealing area and a front facehaving a projection. The projection has a bonding pad provided in anarea surrounded by a contacting area to an upper die, a wiring extendingto the semiconductor element mounting area in one body with the bondingpad, and an electrode provided in one body with the wiring.

Another embodiment provides a process for mounting a semiconductorelement at the semiconductor mounting area and electrically connectingthe bonding pad and the semiconductor element, a process for mountingthe flat member on a die and filling resin into the space provided bythe flat member and the upper die, and a process for separating theprojections respectively by removing the flat member to expose the backface of the resin.

Still another embodiment of the invention is a method for manufacturinga semiconductor device where all of the back face of the flat membercorresponding to the resin-sealing area contacts a lower die.

The contacting area of the lower die can be a scattering vacuum suctionmeans.

The dividing step includes etching an entire surface of the flat memberto a predetermined depth or grinding an entire surface of the flatmember to expose the resin.

The dividing step can also include etching and grinding the flat memberto expose the resin.

Because the flat member is formed in sheet shape, the back face of theflat member is contacted in all faces of the lower die. Moreover, aconductive pattern such as a pad does not make any burr thereof at theback face of the flat member because the conductive pattern is providedin the sealing space.

A conductive pattern and a semiconductor element are sealed withinsulating resin. A flexible sheet is then removed to realize a thin,light semiconductor device. Moreover, by burying a wiring and forming aconductive film on the surface of a conductive foil, a bonding pad or awiring having eaves at its face is formed to provide an anchoringeffect. Therefore, a semiconductor device of a BGA type, which reducesor prevents deformation such as bending and peeling of the conductivepattern, can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flat member of the invention.

FIG. 2 illustrates a flat member of the invention.

FIG. 3 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 4 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 5 shows a flat member of the invention.

FIG. 6 shows a flat member of the invention.

FIG. 7 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 8 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 9 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 10 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 11 shows a flat member adopted as a lead frame.

FIG. 12 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 13 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 14 illustrates a method for manufacturing a semiconductor deviceadopting a flat member of the invention.

FIG. 15 shows a conventional semiconductor device of a BGA structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates a semiconductor device with bonding pads arrangedat a periphery of a semiconductor chip and electrodes in matrix-shapeusing wirings integrated with the bonding pads. Although, the above maygenerally be classified as a BGA in which a solder ball is attached atthe electrode, it is referred here as a semiconductor device of a BGAconstructions.

First Embodiment

FIG. 1A shows a flat member which is made thinner than a conventionalflexible sheet.

In the flat member 10, a conductive pattern that would be printed on aconventional flexible sheet in a BGA is formed with a conductive film11.

That is, the flat member 10 has a first face 12 including a flat faceand a second face 13 including a flat face opposite to the first face12. On the second face 13, a first conductive film 11A withsubstantially the same pattern as a second bonding pad 17 is formed at aperiphery of a semiconductor mounting area 14. The first conductive film11A is provided corresponding to a first bonding pad 16 on asemiconductor element 15 shown in FIG. 3 and is formed in substantiallythe same pattern as the second bonding pad 17. A second conductive film11B has substantially the same pattern as a wiring 18 provided in onebody with the above-mentioned second bonding pad 17. A third conductivefilm 11C has substantially the same pattern as an electrode 19. Theseconductive films 11A to 11C may be made in the same material or not.However, for the conductive films 11A to 11C, the material available foran etching resist mask is selected, and this would be made clear laterin reference to the manufacturing method. For the surface of theconductive film 11A, a bonding wire 20 may include Au or Al inconnection with the ball bonding method or ultrasonic bonding method.

In FIGS. 13A and 13B, the brazing filler metal and conductive paste areselected for the conductive film 11A when a facedown-type element (SMD)is used as the semiconductor element 15.

On the flat member 10, an etching resist mask MSK such as a photo resistmay be formed instead of the conductive film 11 as shown in FIG. 1B. Inthis case, a conductive film 20 is formed at a part corresponding to atleast the second bonding pad 17 so that bonding using a bonding wire ora facedown bonding is possible, and all patterns including theconductive film is covered by a photo resist MSK.

The invention is in the flat member 10. The flat member 10 ishalf-etched through the conductive film 11 or the photo resist MSKthereof. The semiconductor 15 is mounted thereon and is sealed by aninsulating resin 21. The flat member 10 exposed at the back face of theinsulating resin 21 is processed by etching, grinding or polishing etc.untill a conductive pad 22 including the second bonding pad, the wiring18, and the electrode 19 is separated. The semiconductor device isconstructed by three materials: the semiconductor element 15, aconductive pattern 22, and the insulating resin 21 which seals thesemiconductor element 15 and the conductive pattern 22. The flat member10 functions as a semiconductor device 23 of a BGA.

The conductive film 11 or the etching-resist mask MSK is formed on thesurface of the flat member 10 for half-etching.

Generally, lateral directional etching advances with the advance oflongitudinal directional etching. For example, this phenomenon appearsin isotropic etching where the depth of longitudinal directional etchingand the length of lateral directional etching are substantially thesame. In anisotropic etching, the length of lateral directional etchingis shorter than in the case of isotropic etching.

For example, in the semiconductor device with the BGA structure shown inFIG. 15, in the case of forming conductive patterns 53 to 55 on aflexible sheet 50, it would be necessary to remove the patterns to passthrough from the face to the back of the bonded Cu foil. However, theinterval of conductive patterns is etched even to the lateral direction.The interval of the conductive pattern 22 and adjacent conductivepattern thereto cannot be made smaller than a certain limit because ofthe correlation with the thickness of the Cu foil. Even with othersemiconductor devices of a BGA construction adopting etching-type leadframes, a similar phenomenon appears. Even with removing the lead frameby pressing, the thickness of the lead frame is minimal between leads ofthe lead frame so that there would be a limit to the fine pattern thatcan be achieved.

However, by forming the conductive film 11 or the etching-resist maskMSK and then half-etching in depths suitable for fine pattern forming,the etching in the lateral direction is reduced so that finer conductivepattern 22 can be realized.

When conductive film 11 such as Ni, Ag, Au, Pd, as a conductive film isformed on the flat member 10 of thickness of 2 oz. (70 μm) and when thefilm is etched untill entirely passed through using a mask, the intervalof the conductive pattern is about 70 μm in the narrowest case. However,by using the conductive film 11 as an etching-resist mask and by etchingthe flat member 10 to the depth of 35 μm, the interval of the conductivepatterns can be processed to the depth of 35 μm. That is, efficiency isincreased by two fold. The finer pattern is possible because of theshallower depth acheived by half-etching the flat member 10.

In the flat member 10 according to the invention, wet etching isdesirable in consideration of etching facilities, mass-productivity, andmanufacturing costs. However, wet etching is non-anisotropic and etchingin the lateral direction is comparatively large. Therefore, half-etchingusing the conductive film 11 and the etching-resist mask MSK would besuperior for obtaining a finer conductive pattern 22.

In the flat member 10 of the invention, the conductive pattern 22 doesnot slip and bend as long as the flat member 10 is fixed because thehalf-etched conductive pattern 22 is made in one body with the flatmember 10. The flat member can stably bond to the second bonding pad 17.

Support is needed for the conductive pattern with hanging lead in thesemiconductor device with a BGA structure forming the above-mentionedlead frame. However, support is not need for the present invention.Therefore, the conductive pattern 22 is arranged at any position withoutany consideration to crossing the hanging lead. Consequently, the designof the conductive pattern 22 becomes easy.

A guide hole 24 may be provided when mounting the flat member 10 on adie.

The guide hole 24 may be opened before molding by drill, punching, oretching along the pattern patterned by a conductive film or a photoresist into a round shape at a corresponding position with substantiallythe same shape as a guide pin. Inserting the guide pin of the die intothe guide hole 24 makes molding with high positional accuracy possible.

As mentioned above, the conductive pattern 22 is formed by half-etchingthrough the conductive film 11 or the etching-resist mask MSK, and thisis possible to adopt in place of a conventional flexible sheet or aconventional lead frame.

A semiconductor manufacturer generally has plants for front process andback process (back-end process) separately. In the back process moldingadopting the flat member 10, generally etching facilities are not setup. Therefore, the semiconductor manufacturer can manufacture asemiconductor device 23 of a BGA construction using the flat member bysetting up film-making facilities and etching facilities for theconductive film 11 and by purchasing the flat member 10 where theconductive film 11 or the etching-resist mask MSK is formed from a metalmaterial manufacturer that manufacturs lead frames.

The conductive pattern 22 may be have a shape of a wiring havingsubstantially a constant width from an end to other end as shown in FIG.1C. Although, the pad 11A and the electrode 11C of FIG. 1A and FIG. 1Bare rectangular and circular respectively, such shape is optional.

Second Embodiment

The flat member 30 is half-etched through the conductive film 11 oretching-resist mask MSK, and a conductive pattern 22 is formed inprojection shape.

That is, a flat member 30 has a first face 12 including a flat face anda second face 13 having a projection 31 formed in a desired height andbeing formed opposite to the first face 12. The projection 31 includes asecond bonding pad 17 provided at a periphery of a semiconductor elementmounting area 14, a wiring 18 of one body with the second bonding pad,and an electrode 19 provided in one body with the wiring.

The flat member 30 is substantially the same in construction and same ineffect as the flat member 10 described in the first embodiment. Adifference is that the conductive pattern is half-etched.

A semiconductor manufacturer, particularly for back processing, usuallydoes not have plating facilities of a flat member 10 comprising Cu andlithography facilities for etching and so on. Therefore, by purchasingthe flat member 30 having the conductive pattern 22 including theprojection using half-etching, the flat member 30 can be handled as thesame as the conventional lead frame so that it may be possible tomanufacture the semiconductor device 23 of a BGA construction withexisting facilities for back processing.

The conductive pattern 22 comprising the projection can be made bypressing the flat member 10. In this, the first face 12 which may haveprojections should be made flat by polishing or grinding.

Third Embodiment

Manufacturing the semiconductor device 23 with a BGA structure using theabove-mentioned flat member 10 or 30 is described referring to FIG. 1 toFIG. 4. FIG. 2A shows the flat member 10 of FIG. 1A half-etched. FIG. 2Bshows the flat member 10 of FIG. 1B half-etched. FIG. 2C shows the flatmember 10 of FIG. 1C half-etched. In FIGS. 3 and 4, the flat member isassumed to be manufactured similarly as in FIG. 1A and FIG. 2A.

In the flat member 10, the first face 12 and the second face 13 areflat. An etching-resist mask MSK of a conductive film 11 or a photoresist shaped into a conductive pattern 22 are formed on the second face13. In FIG. 1A, the conductive film 11 is formed on all faces of theconductive pattern 22, shown by hatched diagonal lines. In FIG. 1B, aphoto resist MSK is used instead of the conductive film 11 and covers aconductive film 11A formed at a part corresponding to at least a secondbonding pad 17. The photo resist MSK is shown hatched with dots. (ReferFIG. 1 about the above.)

The flat member 10 is half-etched through the conductive film 11 or thephoto resist MSK. The depth of etching is shallower than thickness ofthe flat member 10. By having the shallower depth of etching, theforming of fine pattern is possible.

By half-etching, the conductive pattern 22 projects out from the secondface 13 of the flat member 10 as FIG. 2. The flat member 10 may be madeof Cu material, Al material, Fe—Ni alloy material, a layered product ofCu—Al, or a layered product of Al—Cu—Al. Particularly a layered productof Al—Cu—Al can prevent any bends generating by the difference in thethermal expansion coefficients.

For example, by purchasing the flat member 10 of FIG. 1 from a framemanufacturer if a semiconductor manufacturer has etching facilities forback processing, and by purchasing the flat member 30 which theconductive pattern thereof is half-etched in projection shape if thesemiconductor manufacturer does not have etching facilities, the processcan proceed to the next process. (Refer FIG. 2 about the above.)

A semiconductor element 15 is then fixed to a semiconductor mountingarea 14, and a first bonding pad 16 of the semiconductor element 15 anda second bonding pad 17 are electrically connected. In the figure, abonding wire 20 is used for connection because the semiconductor element15 is mounted face-up. For the facedown mounting, solder bump, brazingmaterial such as solder ball, conductive paste such as Ag and Au,conductive ball, or anisotropic conductive resin can be used forconnection.

In this bonding, the second bonding pad 17 is in one body with the flatmember 30. Moreover, the back face of the flat member 30 is flat.Therefore, the flat member 30 can contact a table of a bonding machineface-wise. Therefore by entirely fixing the flat member 30 on thebonding table without causing the second bonding pad 17 to deviate,bonding energy can be transferred to the bonding wire 20 and the secondbonding pad 17 so that strength of the bonding wire 20 is improved.Fixing the bonding table is possible by providing multiple vacuumsuction holes V for the table as shown in FIG. 9, for example.

For fixing the semiconductor element 15 and the flat member 30, aninsulating adhesive 32 can be used. In considering radiation, fillersuch as Si oxide, Al oxide, and may be mixed the insulating adhesive 32.

Then an insulating resin 21 is formed to cover the conductive pattern,the semiconductor element 57, and the connecting means.

For example, for a sealing using a die, a guide hole 24 is provided onthe flat board, and a guide pin of the die is inserted into the hole.Because the first face 12 of the flat member 30 is flat, the face of thelower die is also formed flat. Any methods of thermal plasticity andthermo-hardening can be used for the insulating resin 21.

The molding can be realized by transfer molding, injection molding,dipping, and painting. As a resin material, thermo-hardening resin suchas epoxy resin can be used for transfer molding, and thermal plasticityresin such as liquid crystal polymer, polyphenylenesulfide can be usedfor injection molding.

The thickness of the insulating resin 21 is adjusted so that upper partfrom the top portion of the bonding wire 20, which is about 100 μm, iscovered. This thickness can be controlled to be thick or thinconsidering the strength of the semiconductor device 23.

In filling, the flat member 30 does not shift because the conductivepattern is formed in one body with the flat member 30. Fixing the lowerdie and the back face of the flat member 30 is realized by vacuumsuction. A depressing pin provided at the die may be used.

In the insulating resin 21, the conductive pattern 22 formed as theprojection 31 and the semiconductor element 15 are buried, and the flatmember 30 below the projection 31 is exposed from the back face of theinsulating resin. (See FIG. 3.)

The flat member 30 exposed at the back face of the insulating resin 21is then removed, and the conductive pattern 22 is separatedindividually.

Various methods may be considered for the separation process; that is,the back face may be removed by any method such as etching and polishingor grinding. For example, scraped chips of the flat member 30 andburr-shape metal extending to the outside encroaches on the insulatingresin 21 so as to be thin. Therefore, grinding is stopped before theinsulating resin 21 is exposed. Then, by separating the conductivepattern 22 by etching, the conductive pattern is formed withoutencroaching the metal of the flat member 30 on the insulating resin 21positioned between the conductive patterns 22. That prevents a shortbetween the conductive patterns 22 of fine intervals.

In half-etching, dispersion of thickness appears on the insulating resin21 between the conductive patterns 22 by dispersion of etching depth.After separating the conductive patterns 22 individually by the etchingmethod, grinding can be conducted to a predetermined thickness.Therefore, a package having a certain thickness can be formed.

Where a plurality of the semiconductor devices 23 are formed, a dicingprocess can be used to separate individually the semiconductor devices23 after the separating process. The dicing line is shown by the thickdotted line.

Although the semiconductor devices are separated individually using thedicing equipment, breaking like breaking a chocolate, pressing, orcutting is also possible.

The conductive pattern 22 exposed at the back face may be exposed at apart corresponding to an electrode 19 as shown in FIG. 4B. For theexposed electrode 19, anisotropic conductive resin can be used forfitting a conductive ball such as a solder ball, and covering aconductive paste such as brazing material (e.g. Bolder) or a Ag paste.

In FIG. 4C, etching is carried out through a photo resist formed on theexposed electrode 19. The exposed electrode 19 is made to project out. Aconductive resin R is arranged so that the exposed electrode 19 would beexposed.

By coating the insulting resin R at the back face as shown in FIG. 4Band FIG. 4C, wiring of the mounting board side can be passed at thelower layer. By the above-mentioned method of manufacturing, a pluralityof the conductive patterns 22, the semiconductor element 15, and theinsulating resin 21 can be made into a light, thin, short, smallsemiconductor device of a BGA structure.

A flexible sheet used as a supporting board can be obviated because theconductive pattern 22 is half-etched and supported in one body with theflat member 30.

Making a fine conductive pattern 22 is possible because the conductivepattern 22, which is half-etched and has a projection, is formed on theflat member 30. Therefore, the width of the conductive pattern 22 andthe interval between the conductive patterns 22 can be narrowed so thata smaller package is realized.

Because of construction of the three elements (a plurality of theconductive patterns 22, the semiconductor element 15, and the insulatingresin 21), the semiconductor device consists of only the necessaryelements, and nonessential material is removed so that a thin typesemiconductor device 23 with reduced cost is realized.

Furthermore, because the second bonding pad 17, the wiring 18 and theelectrode 19 are formed to project by half-etching, and the individualseparation process is carried out after sealing, tie bar and hanginglead(support bar) used for the lead frame would not be needed so thatpattern design becomes easy.

Although only one semiconductor element is mounted in the semiconductordevice of the BGA structure in the discussion above, a plurality ofsemiconductor elements may further be mounted.

Fourth Embodiment

FIG. 5 shows a flat member 10 where a conductive film 11 forms aconductive pattern 22 similarly as in the first embodiment. An etchingresist mask such as photo resist may be formed instead of the conductivefilm 11. In this case, a conductive film is formed at a partcorresponding to a bonding pad, and a photo resist pattern is formed tocover the conductive film.

The pattern forming the pattern of FIG. 1 is shown in FIG. 5. A patternunit 34 surrounded by dotted line corresponds to one semiconductor isreplicated into matrix shape. A die contacting area 35 is formed in ringshape with a designated width and surrounds the pattern units 34. Thatis, the pattern of FIG. 5 shows the conductive pattern formed in onecavity.

At inside of the die contacting area 35, alignment marks 36 and 37 areprovided. A line connecting the alignment marks 36A and 37A shows thedicing line in the lateral direction. A line connecting the alignmentmarks 36B and 37B shows dicing line in the longitudinal direction. Eachalignment mark is formed by at least one short straight line, and thedirection of the blade of the dicing equipment is adjusted byreferencing the alignment marks. Here alignment mark is provided in thedesired interval (margin) so that the blade can dice in desiredaccuracy.

Moreover, outside the die-contacting area 35, a first pattern 38 and asecond pattern 39 for forming a guide hole are formed. The cross of thesecond pattern 39 serves as a centering mark when forming the guide holewith a drill. A guide hole with the same shape as the first pattern maybe provided without forming the pattern.

Fifth Embodiment

The flat member 30 has a shape shown in FIG. 6, and has a projection 31half-etched through the etching-resist mask of the conductive film 11 orthe photo resist as shown for the fourth embodiment. A first alignmentmark 38 and a second alignment mark 39 may be formed in projection shapeby half-etching.

The flat member 30 can behandled similarly as the conventional leadframe, SIP, DIP, QIP, and so on.

That is, a flat member 30 has a first face 12 including a flat face anda second face 13 having a projection 31 formed in a desired height andbeing formed opposite to the first face 12. The projection 31 includes asecond bonding pad 17 provided at a periphery of a semiconductor elementmounting area, a wiring 18 of one body with the second bonding pad 17,and an electrode 19 provided in one body with the wiring 18.

The flat member 30 has each pattern half-etched, and it would bepossible to fix the semiconductor element, to connect electrically, andto seal with existing facilities for back processing.

Six Embodiment

A method for manufacturing the semiconductor device is described withreference to FIG. 5 to FIG. 11.

A flat member 10 is provided as in FIG. 5. Material for the flat member10 is selected in consideration with adhesion of brazing material, andbonding and plating characteristics. They are a conductive foil, whichcan be mainly made of Cu or Al. The conductive foil can be also be analloy of Fe—Ni, a layered product of Cu—Al, or a layered product ofAl—Cu—Al. On the surface of the flat member 10, a second bonding pad 17,a wiring 18, an electrode 19, a die contacting area 35, alignment marks36 and 37, patterns 38 and 39 can be formed by an etching-resist mask ofa conductive film 11 or a photo resist.

It is desired that thickness of the conductive foil used for the flatmember 10 be about 10 μm to 300 μm. In this embodiment, Cu foil of 70 μm(2 oz.) is used. However, the thickness may be more than 300 μm or lessthan 10 μm. (See FIG. 5.)

The flat member 10 is selectively removed except for area providing thesecond bonding pad 17, the wiring 18, the electrode 19, the diecontacting area 35, the alignment marks 36 and 37, and patterns 38 and39. Therefore, the certain regions are thinner than the thickness of theflat member 10.

Here the conductive film 11 or the photo resist is used as anetching-resist mask, and the isolation groove 40 is formed shallowerthan the thickness of the flat member 10.

In the method for manufacturing, the flat member is etchednon-anisotropicaly by wet etching or dry etching, and has acharacteristic that the side thereof has coarse face and made bend.

In the case of the wet etching, ferric chloride or cupric chloride isgenerally used for etchant. The conductive foil, for example, is dippedinto the etchant or the etchant may be sprayed.

Especially, just under the conductive film 11 or a photo resist being anetching mask, etching in the lateral direction advances less than thanat some deeper portion. Thus, the isolation groove 40 would have anopening diameter smaller than a diameter at some deeper portion, so thatthe opening has a reverse-tapered structure to provide an anchoringstructure. By showering, etching is advanced to the depth direction andetching in the lateral direction is suppressed so that the anchorstructure remarkably appears.

In the case of dry etching, both anisotropic and non-anisotropicetchings can be used. Although it is difficult to remove Cu by reactiveion etching nowadays, Cu can be removed by spattering. Depending on thecondition of the spattering, both anisotropic and non anisotropicetchings are possible.

Material for the conductive film can be Ni, Ag, Au, Pt. These corrosiveresistant conductive films can be used by itself for a bonding pad.

For example, a thin Au wire can be bonded to the conductive film of Agand Au. Ni makes ultrasonic bonding with Al wire possible. Therefore,these conductive films can be used by itself for a bonding pad.

In the present embodiment, anisotropic etching can be used to form theprojection. (See FIG. 6.)

A mounting of the semiconductor element 15 on the semiconductor elementmounting area 14 as shown in FIG. 7 is next discussed.

The semiconductor element 15 can be a transistor, a diode, or an ICchip. A CSP of wafer-scale type or SMD (semiconductor element offacedown type) of a BGA can be mounted, although they may increasethickness.

Here, a bare IC chip is fixed by an insulating adhesive 32. A firstbonding pad 16 on the IC chip and a second bonding pad 17 are connectedthrough a bonding wire 20 fixed by thermo-compression bonding or wedgebonding using ultrasonic waves.

The bonding pad 17 shown in the figure is made in one body with the flatmember 30, though the size thereof is very small. Therefore, energy of abonding tool can be transfered to the bonding pad 17 so that bondingability is improved. A bonding wire can be pulled and cut after bonding.Because the second bonding pad 17 is made in one body with the flatmember 30, the bonding pad 17 may be prevented from rising and thepull-cutting process is improved. (See FIG. 7.)

Moreover, an insulating resin 21 may be applied in an isolation groove40. This is realized by transfer molding, injection molding, dipping, orpainting. As resin material, thermo-hardening resin such as epoxy resincan be used for transfer molding, and thermal plasticity resin such asliquid crystal polymer or polyphenylenesulfide can be used for injectionmolding.

In the embodiment, the thickness of the insulating resin 21 is adjustedso that the upper part from the top portion of the bonding wire 20,about 100 μm, is covered. This thickness can be tailored based on thestrength of the semiconductor device 23.

The flat member 30 functions as a supporting board untill the insulatingresin 21 is covered and hardened. A supporting board of a flexible sheetis needed in the conventional BGA, but the present invention does not.

Moreover, because the insulating resin 21 is filled in the isolationgroove 40 having a bended structure, an anchoring effect appears at thispart so that the conductive pattern 22 is effectively prevented frompeeling off from the insulating resin 21.

Putting silicon resin and the like is useful in order to protect theconnecting portion of the semiconductor chip and the bonding wire, forexample, before covering with the insulating resin 21.

FIG. 9 shows a molding method. FIG. 9A is a section view showing theinsulating resin 21 being filled into a cavity 101 in a die 100. Theback face of the flat member 30 contacts a lower die 100A and upper die100B contacts at a die contacting area. The symbol V is a vacuum suctionhole. FIG. 9B shows the flat member 30 being mounted on the lower die100A. Symbol 102 is a guide pin attached at the lower die 100A, and theguide pin appears through a guide hole opened at the flat member 30.

FIG. 9C shows a cavity 101, a runner 103, and a pot 104 formed at thedie. As shown in the figure, the die is designed so that severalcavities 101 are arranged in the lateral direction and many of thesemiconductor devices are taken from one frame. Symbol 105 shown withdotted line shows an arranging area of the flat member, and the flatmember 106 shown in FIG. 11, for example, is mounted similarly as in theconventional lead frame. The flat member 30 as shown in FIG. 6 is formedby using the die where plural cavities and so on are made in one body.The semiconductor device manufactured with the flat member itself issmall in size, and is possible to take many devices in one cavity and tomass produce. This decreases the manufacturing cost. (See FIG. 8 andFIG. 9.)

Removing the flat member 30 exposed at the back face of the insulatingresin 21 and separating the conductive pattern 22 are next discussed.

FIG. 10A shows the separation lines, and FIG. 10B shows that the backface of the insulating resin 21 and the second bonding pad 17, and showshow the back face of the insulating resin 21 and the wiring 18 and theelectrode 19 fit together. This is possible by grinding off usingpolisher or grinder untill the isolation groove 40 is exposed. Only thepart needing electrical connection may be exposed from an insulatingfilm such as a solder resist.

In FIG. 10C, a projection 111 is formed at the other end 110 of theelectrode 19, by stopping the polishing appropriately. This is possibleby forming a photo resist at a part corresponding to the projection 111and by etching except the part. The insulating film R is formed so thatthe projection 111 is exposed. This process can prevent a short on theconductive member of the mounting board side passing under thesemiconductor element 15.

The semiconductor device is completed by arranging the molding member ona dicing table, adjusting position of a blade by referring to thealignment marks 36 and 37, and dicing along the line shown by the dottedline.

Seventh Embodiment

FIG. 12 to FIG. 14 show a semiconductor element 150 of facedown type ona flat member 151 and a manufacturing process of a semiconductor deviceof a BGA structure.

Although a conductive pattern 22 extends from the semiconductor elementmounting area by using a bonding wire 20, it is possible to reduce or toremove the projection by adopting the facedown type. Although thethickness of the package may increase because the top of the bondingwire 20 becomes high, a thin type is possible by adopting the facedowntype.

For the semiconductor element of facedown type, a solder ball 152, orbump of solder or Au instead of the solder ball is used.

In the case of fixing the semiconductor element 150 with brazingmaterial such as solder, the conductive film like the bonding pad can beobviated because an electrode 153 consists of Cu as a main material.However, it may be needed for generating an anchoring structure havingeaves.

The method is very similar to other methods described previously.

A flat member 151 is providing as shown in FIG. 12, and the solder ball152 of the semiconductor element 150 is fixed on the flat member 151.

Next, the flat member is sealed using an insulating resin 154 as shownin FIG. 13.

Finally, the semiconductor device is completed by separating theconductive pattern, removing the flat member 151, positioning at theback face of the insulating resin 154, and dicing along the line shownwith the dotted line as shown in FIG. 14.

A a part corresponding to the electrode may be exposed covering theinsulating resin R on the back face of the package as shown in FIG. 10Band FIG. 10C.

By covering a conductive film with a small etching rate on the flatmember and half-etching through the conductive film, eaves and bendingstructure can be formed to produce an anchoring effect. This isapplicable in all the embodiments.

The method is suitable because Cu and Ni formed on the Cu are etched atthe same rate by ferric chloride or cupric chloride and eaves of made ofNi can be formed by the difference in the etching rate.

The flat member of the invention has a structure for half-etching theconductive pattern through the conductive film or the photo resist.Moreover, the conductive pattern on the flat member can be formed bystop pressing or etching without removing the flat member from front toback. The construction adopting the half-etching process can make theinterval of the conductive pattern narrow so that a pattern for finersemiconductor device of a BGA construction would be possible. Because asecond bonding pad, the wiring, and the electrode are constructed in onebody, deformation is suppressed. Moreover separating the conductivepattern is possible by polishing or etching the back face of the flatmember after entirely sealing the insulating resin so that theconductive pattern can be arranged at the designated position withoutshifting. Further the wiring necessary for the semiconductor device of aBGA construction can be arranged without any deformation.

Arranging all of the conductive pattern area in the resin sealing areacan remove burr generated from the conventional lead frame.

Forming the same pattern as the guide pin can open as the guide holewhen sealing with the insulating resin. As the flat member is set on theguide pin of the die for sealing, resin sealing of high positionalaccuracy is possible.

When constructing the flat member with Cu as a main material andconstructing the conductive film with Ni, Ag, Au or Pd, the conductivefilm can be used as an etching mask. Further when the flat member ishalf-etched, side thereof provides a bended structure and eaves byforming the conductive film at the surface of the conductive pattern.The flat member then has the structure having an anchoring effect.

The semiconductor device manufactured on the flat member consists ofonly the necessary elements of the semiconductor element, the conductivepattern, and the insulating resin. Therefore, the manufacturing cost canbe reduced. Because the supporting board such as a flexible board, whichhas low thermal conductivity, is not used, thermal radiation can beincreased. By optimizing the thickness of film of the insulating resinand thickness of the conductive foil, a small, thin, and lightsemiconductor can be realized.

The exposed back face of the conductive pattern from the insulatingresin can instantly connect to the outside so that the through-hole suchas in the flexible sheet of the conventional structure would not beneeded.

The semiconductor device has a structure having a flat surface where thesurface of the isolation groove and the surface of the conductivepattern are substantially the same. Any shifting of the electrode can beeasily corrected because the semiconductor device itself is only movedhorizontally even when mounting a narrow pitch GFP on the mountingboard.

A side face of the conductive pattern has a bended structure, and eavesare formed at the front face. Therefore it is possible to generate ananchor effecting.

The flat member supports the entire device untill the insulating resinis covered. During the separation and dicing of the conductive pattern,the insulating resin serves to support the structure like a supportingboard. Therefore, the supporting board described in the prior art wouldnot be needed.

1. A board for manufacturing a BGA comprising: a flat member having afirst face and a second face opposite to said first face, said secondface having an area for mounting a semiconductor element; a firstconductive film formed on said second face and provided at a peripheryof the semiconductor element mounting area, said first conductive filmcorresponding to a bonding pad; a second conductive film integrated withthe first conductive film and extending to said semiconductor elementmounting area, said second conductive film corresponding to a wiringintegrated with the bonding pad; and a third conductive film integratedwith the second conductive film and disposed opposite to the firstconductive film, said third conductive film corresponding to anelectrode integrated with the wiring wherein at least some area of theflat member not under the conductive films is partially etched through.2. A board for manufacturing a BGA comprising: a flat member having afirst face and a second face opposite to said first face, said secondface having an area for mounting a semiconductor element; a first photoresist formed on the second face and provided at a periphery of thesemiconductor element mounting area, said first photo resistcorresponding to a bonding pad; a second photo resist integrated withthe first photo resist and extending to said semiconductor elementmounting area, said second photo resist corresponding to a wiringintegrated with the bonding pad; and a third photo resist integrated tothe second photo resist and disposed opposite to the first photo resist,said third photo resist corresponding to an electrode integrated withthe wiring wherein at least some area of the flat member not under thephoto resist is partially etched through.
 3. A board for manufacturing aBGA according to claim 2, wherein a conductive film is provided at areacorresponding to said bonding pad and said photo resist is formed tocover the conductive film.
 4. A board for manufacturing a BGA accordingto claim 1, wherein a substantially same pattern as a guide pin or aguide hole where said guides pin is inserted is formed at side parts ofsaid flat member facing each other.
 5. A board for manufacturing a BGAaccording to claim 1, wherein said flat member comprises a conductivefoil and said conductive film comprises material different from saidconductive foil.
 6. A board for manufacturing a BGA comprising: a flatmember having a first face and a second face opposite to said firstface, and said second face having an area for mounting a semiconductorelement; a first projection formed on said second face and provided at aperiphery of the semiconductor element mounting area, said firstprojection corresponding to a bonding pad; a second projectionintegrated with the first projection and extending to said semiconductorelement mounting area, said second projection corresponding to a wiringintegrated with the bonding pad; and a third projection integrated withthe second projection and disposed opposite to the first projection,said third projection corresponding to an electrode integrated with thewiring wherein at least some area of the flat member not under theprojections is partially etched through.
 7. A board for manufacturing aBGA according to claim 6, wherein a conductive film is formed on surfaceof said projection.
 8. A board for manufacturing a BGA according toclaim 7, wherein a conductive film is formed on at least an areacorresponding to said bonding pad.
 9. A board for manufacturing a BGAaccording to claim 6, wherein said flat member comprises a conductivefoil and said conductive film comprises material different from saidconductive foil.
 10. A board for manufacturing a BGA according to claim6, wherein a substantially same pattern as a guide pin or a guide holewhere said guides pin is inserted is formed at side parts of said flatmember facing each other.
 11. A board for manufacturing a BGA accordingto claim 6, wherein a pattern of said projection is formed in a matrixmanner.
 12. A board for manufacturing a BGA according to claim 6,wherein said flat member comprises Cu, Al, Fe—Ni alloy, layered productof Cu—Al, or layered product of Al—Cu—Al.
 13. A board for manufacturinga BGA according to claim 6, characterized in that side face of saidprojection has an anchor construction.
 14. A board for manufacturing aBGA according to claim 6, characterized in that said conductive filmconstructs eaves at an upper face of said projection.
 15. A board formanufacturing a BGA according to claim 14, wherein said conductive filmis made of anyone of Ni, Au, Ag, and Pd.
 16. A board for manufacturing aBGA comprising: a flat member having a first face as a resin sealingarea and a second face opposite to the first face, said second facehaving a first projection disposed thereon, a second projection, and athird projection within an area surrounded by a contact area to an upperdie; a semiconductor element mounting area within the area surroundingby the contact area; wherein the first projection is provided at aperiphery of the semiconductor element mounting area, and saidprojection corresponds to a bonding pad; the second projection isintegrated with the first projection and extends to said semiconductorelement mounting area, and said second projection corresponds to awiring integrated with the bonding pad; the third projection isintegrated with the second projection and disposed opposite to the firstprojection, said third projection corresponds to an electrode integratedwith the wiring; and at least the area surrounded by the contact area tosaid upper die constructs a sealing space with said second face and saidupper die, wherein at least some area of the flat member not under theprojections is partially etched through.
 17. The board for manufacturinga BGA according to claim 16, further comprising: an insulating layerdisposed in the semiconductor element mounting area.
 18. A board formanufacturing a BGA according to claim 1, further comprising: aplurality of alignment marks provided around the periphery of the flatmember to facilitate dicing of the flat member.
 19. A board formanufacturing a BGA according to claim 2, further comprising: aplurality of alignment marks provided around the periphery of the flatmember to facilitate dicing of the flat member.
 20. A board formanufacturing a BGA according to claim 6, further comprising: aplurality of alignment marks provided around the periphery of the flatmember to facilitate dicing of the flat member.
 21. A board formanufacturing a BGA according to claim 16, further comprising: aplurality of alignment marks provided around the periphery of the flatmember to facilitate dicing of the flat member.